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Morphology and physiology between subspecies and sexes of Cannabis
PROMOTION AND DEVELOPMENT OF EDUCATION, RESEARCH, AND DISSEMINATION OF THE MEDICAL APPLICATIONS OF CANNABIS
CANNABIS IS A MONOTYPIC GENUS PLANT THAT HAS THREE SUBSPECIES, ALTHOUGH NOWADAYS THERE IS MORE TALKING OF HYBRIDIZATION IN THE GENUS AND HERMAPHRODITISM IN THE SEX. THUS, IT IS IMPORTANT TO MAKE BOTH MORPHOLOGICAL AND PHYSIOLOGICAL DISTINCTIONS BETWEEN SUBSPECIES, AS WELL AS A MORPHOLOGICAL DIFFERENTIATION BETWEEN THE SEXES.
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Cannabis is considered as a monotypic genus plant part of the Cannabaceae family. This meaning that there is only one species in the genus, although it is commonly spoken of three: indica, sativa and ruderalis. These are actually subspecies, but each one has unique characteristics. Being in fact the same species, they can be easily crossbred, thus resulting in uncountable hybrids with a greater or lesser genetic similarity to one or the other, that is why is very odd to find pure indica or sativa genetics, since most of the existing varieties are hybrids of the two subspecies that have mixed over the years, these are commonly and commercially know as strains.
Additionally, indica and sativa are the most chosen varieties, since ruderalis is low in THC, but thanks to its shorter cycle it integrates auto-flowering varieties in a certain percentage (we will discuss this in another publication). Therefore, the two most popular subspecies are indica and sativa. Their main characteristics are mentioned below.
ORIGIN
Indica varieties come from the Central Asian and Indian subcontinent (Pakistan, Afghanistan, India, Tibet, Nepal, etc.) regions, due to its mountainous origin they are more resistant to low temperatures and extreme conditions. Sativa, meanwhile, is typical of tropical climates such as Thailand, South India, Jamaica, or Mexico (McPartland, 2017).
The rudelaris species is little known, its origin goes back to Siberia and Kazakhstan; scarce light intensity in these areas made the plant adapt to its environment and to not depend on light exposure for flowering, thus making it extremely interesting for indoor growers who do not have sufficient hours of natural light; It is small and with few branches, its effect is usually more of intoxication.
Sativa is mainly characterized for its great height, long branches and nodes clearly separated one from the other, a widely extended root system and big and thin leaves; it usually produces an energetic, fast, and euphoric effect (see Fig. 1 and 2). On the other hand, indica is small, short, and compact, its root system is compact as well, is has robust stems with wide dark green leaves as well as dense and heavy flowers that produce a physically relaxing powerful narcotic effect, it is commonly used for medicinal purposes. Figura 1 y 2. Cannabis sativa in the vegetative stage, its long and thin leaves can be observed from the early stage as a seedling (left side photo).
Figura 1 y 2. Cannabis sativa in the vegetative stage, its long and thin leaves can be observed from the early stage as a seedling (left side photo).
SIZE
Because sativa is native to tropical areas, the plants are taller and tend to grow more, making them ideal for outdoor growing; while indica plants are small and shrubby, more suitable for indoors.
LEAVES
a) The leaves of sativa plants are characterized for being longer and thinner. They usually have 7 to 9 leaflets (subdivisions of a leaf) (see Fig. 3).
b) The leaves of the indica plants are characterized for being shorter, narrower, and having 5 leaflets. (see Fig. 4).
Figure 1
Figure 2
Figure 3 C. sativa, the thin leaves can be observed.
Figure 4 C. indica leaf with 5 leaflets.
GROWTH
1. Indica tends to grow in clusters around the branches and stem nodes. Plants are more branched with thicker stems.
2. Sativa distributes its growth over the branches, with longer internodal spaces and fewer branches.
FLOWERING
1. Indica is more robust and compact, with heavier and more compact buds.
2. Sativa, meanwhile, tends to have larger buds.
HARVEST
1. Indica plants are used to less time of optimal light and heat conditions and thus, they present a faster flowering of about 45 to 60 days (6-8 weeks).
2. ) Sativa plants, usually needing a stable warm temperature and around 12 hours of light per day year-round take longer to complete flowering: between 60 and 90 days (10-16 weeks).
EFFECTS
Indica contains more CBD and less THC than sativa, hence indica is more used in medical treatments without significant psychoactive effects. These species can cause relaxation and alter the senses, more specifically: touch, hearing, and taste. At high doses they have direct somniferous, sedative, and relaxant effects; additionally, they can relieve pain, reduce stress and anxiety with a completely physical effect (McPartland, 2017). Sativa variety produces a “getting high” sensation with a more energetic, euphoric, and creative effect, enhances concentration, helps fighting depression, and stimulates appetite; it also has a more mental-cerebral effect.
SEX-DEPENDENT DIFFERENCES
Cannabis plants are characterized for being dioecious, this meaning that there are female and male plants in different specimens. For this reason, you need to unequivocally identify the sex of the plants, if you are interested in smoking the flowers (marijuana) you must identify the female individuals and get rid of the males to avoid pollination, so female plants canalize all their energy on cannabinoid generation and not seed production.
SEX-DEPENDENT MORPHOLOGICAL IDENTIFICATION:
MALE
When male plants reveal their sex, they show a cluster of little spheres at the base of the lateral branches called pollen sacs, when these open, they release the pollen responsible for fertilizing the female plants. Thus, when you see a male plant you need to remove it immediately before fertilization occurs (see Fig. 5).
FEMALE
The protagonists for a good “high” are female plants, for they produce the flowers known as “buds” and it is there where the plant concentrates its THC production.
To identify female plants, you need to identify some small calyces from which some white hairs will protrude, these are the style (a prolongation of the plant’s ovary) and the stigma, both are part of the gynoecium commonly known as “pistil”. Their function is to capture pollen (stigma) and to be the conduit (style) through which pollen reaches the plant’s ovules (see Fig. 6).
Avoiding your plants pollination is important because if the pistil comes into contact with pollen, the calyx will become the ovary and it will devote its energy to produce fruits (dried, inedible) and subsequently seeds, instead of buds.
Figure 5 Male plant, pollen sacs can be observed under the leaves.
The spontaneous development of hermaphroditic inflorescences (pistillate flowers containing anthers) on female plants during commercial farming of marijuana creates a problem for growers as the resulting seed formation reduces the quality of the harvested flower (Small, 2017).
Also, female plant’s resource allocation to pollen production, followed by seed production, can result in disproportionately lower levels of terpenes and essential oils (up to 56%) in pollinated flowers compared to unfertilized female flower (Punja and Holmes, 2020).
Flowers:
Pistillate flowers are accompanied by anther formation, leading to the formation of unwanted seeds. In the young terminal inflorescences papillae are developed (stigmatic hairs).
Figure 6 Female plant, the style (white threads) can be observed in the apical part, the gynoecium is found below it.
Inflorescence development:
It converts into many anthers’ clusters. In mature inflorescences, it originates from a central nucleus.
Mature inflorescence:
Individual anthers produced in hermaphroditic inflorescences. Consists of an outer wall (epidermis and endothecium) with a sulcus (stomium) that expands when mature and opens to release pollen grains. Trichomes develop along the anthers’ stomium.
HERMAPHRODITES
Harvest: it has collapsed stigmas and swollen carpels; it also presents pollen grains.
TRICHOMES
Trichomes are extensions of the plant epidermis that have several functions such as absorbing water, regulating temperature, protecting against the sun and predators; Cannabis has special glandular trichomes that secrete resins (sticky compounds) that uses to trap insects or substances that irritate them. They are mainly found in the inflorescences and it is right inside them where the most cannabinoids and terpenes are stored. (MatillaPlant, 2019) (see Fig. 7, 8 y 9).
Through the trichomes we can determine the point of maturity of the plant and so find out when it is best to harvest, depending on the personal interest; trichomes go through four color changes that allow us to know their maturation status, whitish trichomes are the most desirable. (MatillaPlant, 2019).
Transparent trichomes show us that cannabinoid biosynthesis has started and that the plant is not ready to be harvested yet. They look whitish when they have reached the maximum level of cannabinoid, specifically THC (Δ 9- tetrahydrocannabinol); at this precise moment it will provide the maximum psychoactive effects; this of course, only after being dried and “cured”. The amber colored trichomes reach maturity but can only be collected when there are about 10-20% mature; at that moment there is a mixed cannabinoid effect. When it shows a amber / brown color, it is said that the harvest time has passed, since the levels of THC (Δ 9-tetrahydrocannabinol) and CBD (cannabidiol) have greatly decreased; however, other cannabinoids such as CBN (cannabinol) increase, thus offering a more narcotic herb with a relaxing effect (MatillaPlant, 2019).
Figures 7 / 8 / 9 Indoor cultivation plants, hybrids, predominantly sativa, female, in flowering stage, many glandular trichomes can be observed in the apical leaves.
CHEMICAL COMPOSITION AND PHYSIOLOGY
Overall, plants produce two types of metabolites: primary, which are essential for survival, and secondary, which are synthesized by plants for the ecological interaction between the plant and its environment. They are classified into three groups, depending on their biosynthetic origin: terpenes (derived from the IPP compound (Isopentenyl diphosphate or “5-carbon isopentenyl diphosphate”)), phenolic compounds and their derivatives (synthesized by the shikimic acid route or by the malonate / acetate), and alkaloid or nitrogenous compounds (synthesized from amino acids) (Croteau, R., et al, 2000). Furthermore, many of these metabolites have a very restricted distribution, to only a single species or group, such is the case of cannabinoids that can only be found in our favorite plant, Cannabis.
Cannabis has around 500 secondary metabolites derived from different biosynthesis, among which: cannabinoids, terpenes, flavonoids, alkaloids, stilbenes, phenolic amicides and lignanamides (Ángeles López et al., 2014). All of them have important roles for the plant, and we have been able to make the most out of them.
The terpenes in Cannabis are hydrocarbons that differ from complex terpenes by having more diversity of TPS (terpene synthase) enzymes, this provides them greater variety of monoterpenes to synthesize, which gives our plant certain characteristics, like the smell, that helps characterizing our strains; Monoterpenes such as myrcene and sesquiterpenes β-caryophyllene and α-humulene appear to be present in most cannabis “strains”, some others like α-pinene, limonene and linalool, as well as the sesquiterpenes bisabolol and (E) -β -farnesene are responsible for the characteristic smell of each “strain”: Lemon Skunk or Purple Kush, among others (Nikfar and Behboudi, 2014; Booth and Bohlmann, 2019).
Cannabinoids have been extensively studied due to its great biomedical importance. There are about 70 cannabinoids known, D9-THC-a, CBD-a, CBN-a stand out; followed by CBG-a, CBC-a, CBND-a and other compounds in smaller quantities. The “a” at the end, means “acidity”, after decarboxylation it will reach its final form as THC, CBD, CBN, CBG, CBC, and CBND. These are crucial because of their interaction with the endocannabinoid system (discussed later); besides, when synthesized by terpene route, they generally concentrate in the resins produced in trichomes. Their psychotropic effect is also documented, but we will discuss this in further publications (Flores Sánchez and Verpoorte, 2008; Ángeles López et al, 2014).
Flavonoids are aromatic compounds mainly found in leaves, some of them, like canflavin A and B, have shown pharmacological activity inhibiting the production of prostaglandin E, while other studies suggest they regulate the action of cannabinoids (Ángeles López et al, 2014).
Other chemical components such as alkaloids are mainly found, although to a lesser extent, in roots, stems, leaves, pollen and / or seeds, but due to their low concentrations they have not been evaluated for ther pharmacological activity. The stilbenes lignanamides and phenolic amides work together as defense mechanisms; antibactericide, antifungal, anti-inflammatory and neuroprotective properties, among others, have also been attributed to them. Lastly, different lignanamides and phenolic amides with cytotoxic, anti-inflammatory, antineoplastic and analgesic activity have been identified (Ángeles López et al, 2014).
Finally, we would like to emphasize that Cannabis is a exceptional and medically important plant due to its botanical and chemical characteristics for it produces a unique metabolite very useful against several diseases; knowing more about Cannabis could be helpful, since it is of great interest not only for adult recreational purposes use but also for medical uses; therefore, its regulation should be of benefit for most of population.
References:
1 - The greenhouse gas emissions of indoor cannabis production in the United States. Hailey M. Summers, Evan Sproul & Jason C. Quinn https://doi.org/10.1038/s41893-021-00691-w 2 - Bioeconomía en América Latina y el Caribe Contexto global y regional y perspectivas. Adrián G. Rodríguez Andrés O. Mondaini Maureen A. Hitschfeld https://www.cepal.org/es/publicaciones/42427-bioeconomia-america-latina-caribe-contexto-global-regional-perspectivas 3 - Naciones Unidas. Objetivos y metas de desarrollo sostenible: 17 objetivos para transformar nuestro mundo https://www.un.org/sustainabledevelopment/es/sustainable-development-goals/ 4 - Economic Viability of Industrial Hemp in the United States: A Review of State Pilot Programsers.usda.gov/webdocs/publications/95930/eib-217.pdf 5 - Dr. Ethan Russo 1% THC Limit for Hemp World-renowned neurologist and cannabis and endocannabinoid scientist explains why increasing hemp’s allowable THC content makes sense. https://www.hempgrower.com/article/dr-ethan-russo-1-is-a-scientifically-defensible-thc-limit-for-hemp/
Dr. Raúl Porras
Pro Secretary of the Consejo Mexicano de Cannabis y Cáñamo. Medical Surgeon, PhD in Biomedical Sciences at the Instituto Nacional de Enfermedades Respiratorias (INER).
Certified in Cannabis medicine; he applies his knowledge advising patients under cannabis treatment. Member of the International Association of Cannabinoid Medicine (IACM). Founder and president of Cannapeutas A.C.
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